The present invention relates to an art that connects a host computer and plural storage devices, and more particularly, to the control of various functions with which a storage device such a disk array provides the user.
In recent years, the intelligent formation of a computer storage device that is typically represented by a disk array is advancing. For example, a mirror function which a disk array device provides, when a host computer updates data of a storage area in the disk array device, automatically writes the update data even to another predetermined storage area. The storage data at that time is saved by instructing the disk array device to suspend the mirror function and can be used for an application such as backup. Because the writing of update data to another area is executed by a controller in the disk array device, a load is not imposed upon the host computer and high-speed input/output processing is enabled (for example, refer to U.S. Pat. No. 5,845,295).
On the other hand, the number of storage devices in a system increases and the storage devices of different types are intermixed. That is, the storage devices having different protocols are intermixed. At this point, “function” means capabilities to perform mirroring, take a snapshot, and so on provided by storage device, and “function control” means that control is performed so that a host computer can make the storage device implement these functions.
The host computer controls a function by accessing a function control interface which a disk array provides and sending an instruction according to a protocol unique to a predefined storage device. The function control interface can be realized in various forms such as an in-band SCSI command and TCP/IP communication via a LAN (for example, refer to U.S. Pat. No. 5,867,736).
Moreover, the spread of a storage area network (SAN) that connects plural host computers with plural storage devices through a network is advancing. The SAN is a high-speed network dedicated to data input/output that is typically a Fibre Channel and can improve the input/output performance of a computer. Further, the various utilization of storage areas is enabled, that is a computer group connected through the SAN can share one storage device, and, conversely, one computer can access plural storage devices. Recently, it has begun to introduce the art of storage virtualization that not only achieves sharing of a storage device/storage area but concatenates or partitions a storage area (disk volume) which a storage device provides and provides a host computer with a virtual storage area (virtual volume) to realize the flexible management of storage area.
In a computer system in which plural storage devices of different types are intermixed, such as SAN environment, when an intelligent function a storage device provides is utilized, a host computer must identify the type of a disk array to be controlled and send a function control instruction through an interface unique to each storage device. The control is complicated because even in the case to control similar functions, different control programs must be prepared for all different devices and used properly in the host computer.
Moreover, it is considered in the storage virtualization that intelligent functions work on virtual volumes are realized utilizing functions provided by storage devices. In this case, if a virtual volume has plural disk volumes, the function control must be instructed per disk volume. Accordingly, because a host computer must identify a device that provides the actual storage area of the virtual volume and use a control interface unique to each device, the control is complicated.